Where two ends of a cable such as a telecommunications cable are spliced together, the splice area is ordinarily housed within a protective cover known as a closure. Common to substantially all closures is the requirement that they restrict moisture ingress. The integrity of seals which are used to restrict moisture ingress is important especially because of transmission parameters which are readily effected by changes in the moisture content within the cable. Also, common to most closures is the provision of some degree of cable strain relief to prevent splice separation.
Such closures often have included cylindrical covers with one or more longitudinal joints and end plates that surround incoming and outgoing cables and that form seals with the covers. An example of a prior art closure is shown in U.S. Pat. No. 3,636,241 which issued on Jan. 18, 1972 in the names of R. G. Baumgartner et al. Closures which are effective in providing protection for the splice connections are available in the marketplace, but their assembly is relatively time consuming, often requiring specialized tools and equipment which in a limited space such as an underground tunnel are difficult to handle and operate.
To prevent the ingress of moisture some systems employ dry air, nitrogen or a similar chemically inert gas in the cables and closures. In this type of closure, the gas is pressurized to create a flow from enclosed equipment through any openings and prevent the ingress of moisture. In such a system, it is advantageous to minimize the amount of gas leakage to reduce the consumption of gas needed to maintain adequate pressure throughout the system. Accordingly, closures and associated equipment should be sealed adequately to prevent a reduction in pressure and the loss of gas. At the same time it is necessary to provide a system which is easily assembled in the field and in which the probability of installer error is relatively low.
Heretofore a number of closure designs which can provide effective sealing have been available. One major problem with earlier designs has been the need for close tolerances and interference fits. Mechanisms requiring close tolerances and interference fits often are easily damaged in the field where assembly is performed, are expensive to manufacture, and also may require close attention to assembly. These considerations add significantly to both the initial cost of the closure and to the cost of its assembly in the field.
In a closure shown in U.S. Pat. No. 4,181,814, a gasket extends along the longitudinal split in hinged covers. Integral with the gasket at each end thereof is a transverse portion which is wrapped about the periphery of an end plate to form a seal between the end plate and enclosing cover portions. The longitudinal gasket is tapered as are channer members in which it is received to permit a wedge-shaped retainer to compress the gasket and provide a seal.
Despite their design, such closures may still admit moisture where they are improperly assembled. To overcome an inability to assemble simply and seal reliably such closures, reliance often has been placed on the extensive use of a mastic sealing material. However, the extensive use of mastic material often requires substantial installer preparation.
In the recent past, closures have been filled to provide moisture protection or sealed in ways other than with pressurized gas. One known closure utilizes a rigid outer cover, but is filled with a viscous waterproofing material. Another commonly used closure includes a heat shrinkable sleeve. In addition to requiring special heating tools, there is a potential for deterioration of the integrity of the sleeve material due to overheating.
Not infrequently, due to line failure or routine maintenance, one or more cables must be joined or ones of the conductors are rejoined to others. Thus the reentry of and the effective resealing of the closure becomes necessary. Accordingly, the reentry of the closure and its resealing should be made as easy as possible. Obviously, the reentry of closures that are filled with a waterproofing material or that rely on the extensive use of a mastic material becomes a time-consuming task for a craftsperson. For access to the splice area, the filling or mastic sealing material must be removed, creating problems in removal, temporary storage or disposal.
There is still a need for a closure which facilitates reentry and subsequent reassembly. Such a closure is desirable where known future changes will be required in splice connections or where strong possibilities of such changes exist. Seemingly, the prior art does not include a relatively inexpensive, reliable closure which is easy to install to cover splices of pressurized communications cables, for example, and which allows simple reentry to the splice and subsequent reassembly.